The Check Sent Items activity checks the Outlook Sent Items for a message matching all of the conditions and returns true if a message is found.

Setting	Meaning
ActivityID	A unique identifier for the activity
Filter	The field in the message to be checked
Filter Value	The value that the filter must be to match

Note that if a message is found, the following environment variables are set:

from	The sender's e-mail address
to	The recepient's e-mail address
subject	The subject line of he message
message	The body of the message

Also the message is removed from Outlook.